Vat indigoid dyestuffs from dihalogeno-alkylisatins



Patented Jan. 8, 1929.

"UNITED STATES PATENT OFFICE.

CA RL KRAUSS, OF LEVERKUSEN," NEAR COLOGNE-ON-THE-RHINE, GERMANY, AS-

SIGNOB TO GRASSELLI DYESTUFF CORPORATION,

' PORATION OF DELAWARE.

OF NEW YORK, N. Y., A COR- YAT INDIGOID DYIQSTUFFS FROMDIHALOGENO-ALKYLISATINS.

No Drawing. Application'filed October 25, 1926, Serial No. 144,191,.andin Germany November 25, 1925.

in which two of the Xs in each benzene nucleus stand for a halogen atomparticularly chlorine or bromine and at least one of the Xs in eachnucleus for an alkyl group. They can be produced as described in myco-pending patent application Serial No.

143,796 filed Oct. 23, 1926, by condensing a dihalogeno-alkyl-isatincompound containing a reactive substituent in alpha position with adihalogen-alkyl-indoxyl but my preferred process is to reducedihalogeno-alkyl-isatin compounds containing-a reactive substituent inalpha position.

Such reactive substituents are the halogen atoms, particularly chlorine,sulfur, arylamino groups, alkoxy groups, etc.

A very convenient manner of producing these symmetricaltetrahalogeno-alkyl-indigos is to reduce the dihalogeno-alkyl-isatinalpha chlorides with hydrogen sulfide.

The following example will further illustrate my invention, the partsbeing by weight,

but it is understood that my invention is not limited to the specificmaterial and reaction conditions mentioned therein.

Emample 1.-23 parts 5-7-dichlor0- 6-methylisatin are dissolved inchlorobenzene and treated with 25 parts phosphorous pentachloride. Intothe so obtained solution of the alpha chloride one introduces at 90 C. acurrent of hydrogen sulfide gas. The alpha chloride is reduced to theindigo which separates and is isolated in the usual manner. It

is in the dry state a dark blue powder, soluble in concentrated sulfuricacid with a green color, it has most probably the formula 1 1'1 1'1 1 Itforms a yellow vat from which cotton is dyed beautiful, fastreddish-blue shades.

Ewample 2.24.-.4t parts 4-6-dimethyL5-7- dichloroisatin are dissolved in400 parts chlorobenzene, treated with 25parts of phosphorouspentachloride, heated to 90C. Into the so obtained solution of the alphachloride one introduces at 90 C. a current of hydrogen sulfide gas forso a long time until all the dyest-ufi' is separated. The working up isCH OH:

performed in the'ii' sual manner. The dyestufl is in the dry state adark blue powder soluble 1n concentrated sulfuric acid with a greiancolor and has most probably the formu -a I CHI It forms a yellow vatfrom which cotton is dyed beautiful, fast blue shades.

Iclaim: 1. In processes of producing symmetrical 1nd1go1d vat dyestulfsthe step consisting in reducing a dihalogeno-alkyl-isatin compound ofthe formula:

in which two of the Xsstand for halogen substituent.

2. In processes of producing symmetrical indigoid vat dyestuffs the stepconsisting in treating with hydrogen sulfide a dihalogenoalkyl-isati-nalphachloride of the formula in which two of the Xs in each benzenenucleusstand for halogen atoms of an atomic weight of not more than 80and not less than and at least one of the Xs in each benezene nucleusfor an alkyl group, which are a dark blue powder, soluble inconcentrated sulfuric acid with greenish colors and forming yellow vatsfrom which cotton is dyed fast blue shades.

5. As new products symmetrical indigoid vat dyestull's of the generalformula x o 'X I [I in which two of the Xs in each benezene nucleusstand for bromine or chlorine atoms and at least one of the Xs ineachbenzene nucleus for an alkyl group, which are dark blue powders, solublein concentrated sulfuric acid with a greenish color and forming yellowvats from which cotton is dyed fast blue shades.

6. As a new product the symmetrical indigoid vat dyestuffs having mostprobably the formula t i C] \E t /\N/ ti 1';

which is a dark blue powder, soluble in concentrated sulfuric acid wltha green color and forming a yellow vat from which cotton is dyed fastreddish-blue shades.

In testimony whereof I have hereunto set my hand.

CARL KRAUSS.

CH: CH;

